Join the following pipet tips to the Y-shaped connector. Cut 2 pipet tips at 65 mm from the wide end, and connect the narrow end (with a ∼2 mm opening) to 2 test vials. These openings will limit the U-turns once the flies enter the tubes containing the odors. Cut 1 pipet tip at 35 mm from the wide end, and connect it to the loading vial.
Y-maze
Simonnet, M. M., Berthelot-Grosjean, M., Grosjean, Y. Testing Drosophila Olfaction with a Y-maze Assay. J. Vis. Exp. (88), e51241, doi:10.3791/51241 (2014).